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Stratified Fisher's exact test and its sample size calculation.

Sin-Ho Jung1

  • 1Samsung Cancer Research Institute, Samsung Medical Center, Seoul, Korea; Department of Biotatistics and Bioinformatics, Duke University, Durham, NC 27710, USA.

Biometrical Journal. Biometrische Zeitschrift
|January 8, 2014
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Summary

This study introduces an exact testing method for stratified 2x2 tables, extending Fisher's test for situations with rare cell frequencies. It also provides a sample size calculation method for improved study design.

Keywords:
Conditional type I errorExact testHypergeometric distributionMany 2 × 2 tablesOdds ratio

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Area of Science:

  • Biostatistics
  • Epidemiology
  • Clinical Trials

Background:

  • Traditional chi-squared tests for 2x2 tables require large sample sizes.
  • Fisher's exact test is used for small sample sizes.
  • Stratified analysis improves power in heterogeneous populations, with Mantel-Haenszel test being a common large-sample approximation.

Purpose of the Study:

  • To develop an exact testing method for stratified 2x2 tables.
  • To provide a sample size calculation method for studies with rare cell frequencies.
  • To offer a stratified extension of Fisher's exact test.

Main Methods:

  • Developed an exact testing procedure for stratified 2x2 tables.
  • Demonstrated simplification to standard Fisher's test for single tables.
  • Proposed a sample size calculation method tailored for rare cell frequencies.

Main Results:

  • The proposed method provides an exact test for stratified 2x2 tables.
  • The method simplifies to Fisher's exact test in the absence of stratification.
  • A practical sample size calculation method is presented.

Conclusions:

  • The new exact testing method is a valuable tool for analyzing stratified 2x2 tables.
  • The sample size calculation method aids in designing studies with sparse data.
  • This approach enhances statistical power in stratified analyses, especially with rare events.